A technique disclosed in Patent Document 1 relates to an occupant detection sensor that outputs a weight-dependent value to detect an occupant seated on a vehicle seat. Application of the technique of Patent Document 1 may make it possible to test whether the occupant detection sensor normally operates based on whether the output value corresponds to the weight.    Patent Document 1: JP-2005-145362A
There are a weight-type sensor and a capacitive sensor as types of occupant detection sensor. The weight-type sensor determines an occupant based on a weight as is the case of the technique of Patent Document 1. The capacitive sensor determines an occupant based on an electrostatic capacity change. As for this capacitive sensor, the electrostatic capacity of an occupant cannot be simulated by the weight alone. Therefore, application of the technique of Patent Document 1 cannot make it possible to test whether the capacitive sensor normally operates.
When a person (human body) is directly seated on the seat, the deployment of the air bag is required. By contrast, when an infant is seated on a child restraint system (e.g., child seat) attached to the seat, the deployment of the air bag is not required. The person and the infant on the child restraint system (e.g., one years of age) have different electrostatic capacities. From this point, a conceivable testing method involves a person who is actually seated and a child restraint system that is actually mounted. In these cases, however, the testing becomes complicated. Therefore, a testing apparatus or method capable of testing a capacitive occupant detection sensor in a simple way is desired.